From: Ralf Baechle <ralf@oss.sgi.com>
To: Shuanglin Wang <swang@mmc.atmel.com>
Cc: linux-mips@oss.sgi.com
Subject: Re: MIPS and pci_alloc_consistent()?
Date: Wed, 10 Oct 2001 13:38:32 +0200 [thread overview]
Message-ID: <20011010133832.B13349@dea.linux-mips.net> (raw)
In-Reply-To: <3BC36AE4.4D1EE63E@mmc.atmel.com>; from swang@mmc.atmel.com on Tue, Oct 09, 2001 at 04:23:49PM -0500
On Tue, Oct 09, 2001 at 04:23:49PM -0500, Shuanglin Wang wrote:
> I tried to use the pci_alloc_consistent() to allocate one-page DMA'able
> memory for my device driver. But, when booting up the system, it was
> always failed to execute the pci_alloc_consistent() by showing some
> memory errors.
>
> I traced the code to the function __alloc_page() in the file
> mm/page_alloc.c, and found the system called "wakeup_kswapd()". But at
> that time, the kswapd process pointer is a NULL pointer and the
> wakeup-related codes don't check the pointer is NULL or not, so the
> system was stopped because of dereferencing the null pointer.
This sounds like either memory corruption has overwritten the kernel pointer
or you're trying to use pci_alloc_consistent before the memory managment
is initialized.
> Anybody has some ideas about the problem? Or are there other convenient
> methods to allocate DMA'able memory?
Anything else than the pci_alloc_* functions isn't portable.
Ralf
prev parent reply other threads:[~2001-10-10 11:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-10-09 21:23 MIPS and pci_alloc_consistent()? Shuanglin Wang
2001-10-10 11:38 ` Ralf Baechle [this message]
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